The moment I reinsert the SD card, Windows Phone 10 begins recreating the deleted WPSystem folder with all its contents. Making the "duplicates" again. Total size of the folder after a day: 1.86 GB - Basically Windows fills my whole SD card until there are no bytes left to steal...Yes, I have a lot of pictures, mostly game development related, e.g.: about a thousand individual frames forming small, animated sprites.The thumbnails are often bigger than the pictures themselves: An 8x8 sprite is about 100 bytes, which is small enough to be stored inside the partition's File table itself, directly after the filename. So their actual "size on disk" is zero, with no sectors wasted, just a file name entry in the MFT.* The respective thumbnail however, takes up 5 kilobytes, meaning it's about 50 times bigger than the picture itself. (5000%) This thumbnail actually wastes two sectors (8KB) provided the allocation unit size is left at the default 4096 bytes.Larger, more complex (multi-frame) sprites are worse; they get blown up (fuzzy resampled instead of simply resized 1:1), meaning they don't even compress well. A 64x64 pixel unit portrait got exploded into a 4MB ugly blur, for example. Four megabytes! To store a mere unit icon!? I checked; The resulting picture was over 2000 pixels wide. And they call that a thumbnail? The original was only 60 pixels, now that's a true thumbnail. Why not simply use that?Doesn't help that while the file extension is jpg, the actual file headers state the truth: ‰PNG... Which is usually 2x-8x as big as the jpg equivalent. And since the images become terribly blurry anyway from the resample process, having crisp, lossless png is pointless. Just an even bigger waste of storage space. (The original pixel art sprites are naturally stored in png. But that makes sense, since each pixel counts. At least the thumbnails aren't raw bmp...)What I need is to write-protect that stupid folder, protecting it from windows itself. Or blank all the 1000 files individually and then prevent the phone from touching them again. Simply deleting the files does nothing in the long run.

*The master file table allocates a certain amount of space for each file record. [...] Small files and directories (typically 512 bytes or smaller) [...] can entirely be contained within the master file table record.